Zone of War

You were left alone to defend the base because your troops were recalled into the main camp. The enemy learned of this and decided to take the base for themselves, but they are not ready for you as you are brave enough to take them down. You have a high-ground so you can see everything.
You need to defend the base against invading force. You need to hit them first before they can even fire since you can't dodge the bullets. The game gets more difficult as you make some progress.
Are you ready to be a hero and defend the base all by yourself?